EP2098741A2 - Mechanical disconnect dual-sided interlocking teeth - Google Patents
Mechanical disconnect dual-sided interlocking teeth Download PDFInfo
- Publication number
- EP2098741A2 EP2098741A2 EP09153008A EP09153008A EP2098741A2 EP 2098741 A2 EP2098741 A2 EP 2098741A2 EP 09153008 A EP09153008 A EP 09153008A EP 09153008 A EP09153008 A EP 09153008A EP 2098741 A2 EP2098741 A2 EP 2098741A2
- Authority
- EP
- European Patent Office
- Prior art keywords
- teeth
- generator
- ball screw
- engagement member
- engine
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Withdrawn
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Classifications
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F16—ENGINEERING ELEMENTS AND UNITS; GENERAL MEASURES FOR PRODUCING AND MAINTAINING EFFECTIVE FUNCTIONING OF MACHINES OR INSTALLATIONS; THERMAL INSULATION IN GENERAL
- F16D—COUPLINGS FOR TRANSMITTING ROTATION; CLUTCHES; BRAKES
- F16D11/00—Clutches in which the members have interengaging parts
- F16D11/02—Clutches in which the members have interengaging parts disengaged by a contact of a part mounted on the clutch with a stationarily-mounted member
- F16D11/04—Clutches in which the members have interengaging parts disengaged by a contact of a part mounted on the clutch with a stationarily-mounted member with clutching members movable only axially
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F16—ENGINEERING ELEMENTS AND UNITS; GENERAL MEASURES FOR PRODUCING AND MAINTAINING EFFECTIVE FUNCTIONING OF MACHINES OR INSTALLATIONS; THERMAL INSULATION IN GENERAL
- F16D—COUPLINGS FOR TRANSMITTING ROTATION; CLUTCHES; BRAKES
- F16D23/00—Details of mechanically-actuated clutches not specific for one distinct type
- F16D23/12—Mechanical clutch-actuating mechanisms arranged outside the clutch as such
- F16D2023/123—Clutch actuation by cams, ramps or ball-screw mechanisms
Definitions
- the present invention generally relates to apparatus and methods for disengaging generators and other rotating machines from a prime mover and, more particularly, to apparatus and methods of disengaging an aircraft generator from an engine or gear box to prevent damage to the engine or gear box.
- the generators may be coupled to the main engine or to auxiliary power units through a gear box.
- Known designs of generators have a generator drive shaft that includes some kind of shear section that is based on safe operational capability of the gearbox. In the event that the generator malfunctions, this shear section operates and protects the gear box from continuing to rotate under an unacceptable load from a malfunctioning generator that may have stopped rotating.
- the design of the shear section is not difficult - it is easy to design a shear section to meet one speed.
- VFG variable frequency generators
- Such a protection means should not interfere with proper engagement of the generator with the gearbox irrespective of whether a generator shaft is producing load on the gearbox or alternatively when the gearbox may be producing mechanical load on the generator shaft.
- a dis-engageable generator drive system comprises a first engagement member coupled to a generator, and a second engagement member coupled to an engine.
- the engagement members have a plurality of circumferentially disposed teeth.
- the teeth have a distal circumferential width at their distal ends and a proximal circumferential width at their proximal ends wherein the distal circumferential width is greater than the proximal circumferential width.
- the engagement member has a plurality of circumferentially disposed teeth.
- the teeth have a distal circumferential width at their distal ends and proximal circumferential width at their proximal ends wherein the distal circumferential width is greater than the proximal circumferential width.
- a method of driving a generator with an engine comprises the steps of Interlockingly engaging the engine with an inner ball screw having an angled threading on an outer surface thereof, engaging the inner ball screw with an outer ball screw that rotates with the inner ball screw, including an angled ball track between the inner ball screw and the outer ball screw on which a ball bearing travels, and actuating a brake to slow or stop rotation of the outer ball screw so that the inner ball screw rotates relative to the outer ball screw along the ball track and slides axially away from the engine thereby disengaging the generator from the engine.
- Figure 1 is a sectional view of a drive system wherein a generator is in its normal state engaged with an engine in accordance with the invention
- Figure 2 is a sectional view of the disengagement assembly of Figure 1 wherein the generator is disengaged from the engine in accordance with the invention
- FIG. 3 is a perspective view of a generator-side engagement member in accordance with the invention.
- Figure 4 is a perspective view of an engine-side engagement member in accordance with the invention.
- Figure 5 is a graphical representation of teeth and recesses of the engagement members of Figures 3 and 4 in accordance with the invention.
- Figure 6 is a graphical representation of teeth and recesses of the engagement members of Figures 3 and 4 in accordance with the invention.
- Figure 7 is another graphical representation of teeth and recesses of the engagement members of Figures 3 and 4 in accordance with the invention.
- Figure 8 is a graphical representation of teeth and recesses of the engagement members of Figures 3 and 4 in a disengaged state in accordance with the invention.
- Figure 9 is a flow chart showing a method in accordance with the present invention.
- the present invention generally provides a disengagement assembly for a rotating machine, such as an aircraft generator, for disengaging the generator from an engine or gear box.
- a rotating machine such as an aircraft generator
- the drive shaft of the generator may be rotating and operatively engaged to the drive shaft of the gear box.
- the disengagement assembly may allow a pilot to disengage the generator from the gear box.
- the disengagement assembly may be a modular or standalone assembly having its own housing separate from the housing of the generator, or alternatively the disengagement assembly may be subsumed within the housing of the generator.
- the disengagement assembly may be used in aircraft and may be re-settable manually on the ground after repair of the generator.
- the disengagement assembly of the present invention may utilize a ball screw mechanism to provide a desired axial positioning of novel engagement teeth which maintain an interlocking relationship with one another irrespective of direction of torque application during proper operation of the generator.
- the interlocking teeth may disengage from one another in the event of a malfunction of the generator.
- the disengagement assembly of the present invention may be resettable and reusable.
- a generator drive system 10 may be provided with a disengagement assembly 11 for disengaging a variable frequency generator 12 from a gear box 13 of a prime mover or engine 14.
- the disengagement assembly 11 may comprise a rotatable inner ball screw 16 that has angled threading 16-1 on an outer surface 16-2 of inner ball screw 16.
- inner ball screw 16 may be hollow, inner ball screw 16 may surround and may be operatively engaged to a generator drive shaft 18 so that the rotation of generator drive shaft 18 on an axis 19 may cause rotation of inner ball screw 16.
- the splines 20 or another suitable structure may serve to transfer rotational force of the generator drive shaft 18 to inner ball screw 16.
- Inner ball screw 16 may have an engagement member 22, at an end distal to the generator 12. This engagement member 22 may be normally engaged to a corresponding engagement member 24 which may be connected to the gearbox 13 or optionally to the engine 14 if a gearbox is not utilized.
- Disengagement assembly 11 may also include an outer ball screw 26 which may surround and may normally rotate with inner ball screw 16.
- outer ball screw 26 may have associated with it one or more balls 28, called ball bearings, that travel on an angled ball track 30 that exists between the inner ball screw 16 and outer ball screw 26. In one exemplary embodiment, there may be between approximately five and seven such balls depending upon the design requirement.
- the angled ball track 30 may be formed from threading 16-1 on the inner ball screw 16 and outer threading 26-1 formed on the outer ball screw 26. The fact that the ball track 30 is angled means that ball track 30 has some axial component rather than simply being a series of revolutions around inner ball screw 16.
- Disengagement assembly 11 may also include a brake 38 that may be capable of slowing or stopping rotation of outer ball screw 26.
- a brake 38 slows or stops rotation of outer ball screw 26
- this slowing or stopping of the rotation of outer ball screw 26 may cause inner ball screw 16 to rotate relative to outer ball screw 26 along ball track 30 and simultaneously slide axially away from the engine 14 thereby disengaging the generator 12 from the engine 14.
- inner ball screw 16 slides axially away from engine 14
- inner ball screw 16 may be sliding on generator drive shaft 18, and more precisely on splines 20 between the surface of generator drive shaft 18 and inner surface 16-3 of inner ball screw 16.
- outer ball screw 26 may be capable of rotation and inner ball screw 16 may be capable of both rotation and axial movement.
- the brake 38 may be connected to a solenoid 40 that may be remotely actuatable by an aircraft pilot when generator 12 malfunctions. Other arrangements may easily be imagined whereby brake 38 may be controlled directly or indirectly with other mechanisms.
- the engagement member 22 may include interlockable teeth 22-1 and the corresponding engagement member 24 of the gear box drive shaft adaptor 14 may also include interlockable teeth 24-1 that mate with the teeth 22-1.
- the teeth 22-1 may be positioned circumferentially around the engagement member 22. It may also be noted that while an exemplary number of eight of the teeth 22-1 are shown in Figure 3 , each of the teeth 22-1 covers only about 15 degrees of angular displacement around the circumference of the engagement member 16. Recesses 22-2 between the teeth 22-1 cover a larger portion of the circumference than the teeth 22-1. Each of the recesses 22-2 may cover about thirty degrees of angular displacement of the circumference.
- recesses 22-2 may be about twice as wide as their respective adjacent teeth 22-1.
- the engagement member 24 shown in Figure 4 may also be provided with similar teeth 24-1 and recesses 24-2 which may interconnect and interlock with the teeth 22-1 and recesses 22-2 of the engagement member 22.
- each of the teeth 22-1 may be formed with a proximal end 22-3 smaller than a distal end 22-4.
- each of the teeth 22-1 may be formed with a profile that resembles a truncated pyramid.
- Each of the recesses 22-2 may be formed with a proximal end 22-5 larger than a distal end 22-6.
- Tooth sides 22-7 may be formed at an angle A relative to an axis 19 of the generator 12 of Figure 1 .
- Tooth sides 22-8 may be formed at the angle B relative to the axis 19.
- the engagement member 24 may have its teeth 24-1 and its recesses 24-2 formed in the same manner as the teeth 22-1 and the recesses 22-2 of the engagement member 22.
- Figures 5 , 6 and 7 are intended to provide a readily understandable graphical representation of the interlocking nature of the teeth 22-1 and 24-1 and the recesses 22-2 and 24-2. As such Figures 5 , 6 and 7 may not show their respective objects in scale.
- the angles A and B may be equal in magnitude and opposite in direction relative to the axis 19. The angles A and B may be between about three degrees and about one degree.
- Each of the teeth 22-1 and 24-1 may have a height H of about 0.050 inch to about 0.150 inch.
- the engagement member 22 may have a diameter of between about 2 inches to about 3 inches.
- each of the recesses 22-2 and 24-2 may have a distal width of between about 0.50 inch and 0.80 inch.
- Each of the teeth 22-1 and 24-1 may have a distal width of about 0.25 inch to about 0.40 inch.
- FIG. 6 it may be seen how the teeth 22-1 and 24-1 interact with one another when the engine 14 or its gearbox 13 may apply a torque load to the generator 12, i.e. when engagement member 24 drives engagement member 22.
- Figure 6 shows a direction of rotation arrow 62 portraying a counterclockwise rotation of the generator 12 and the engine 14.
- Left-hand sides 24-7 of each of the teeth 24-1 may engage with and produce circumferential force on right-hand sides 22-8 of the teeth 22-1.
- each of the teeth 22-1 and 24-1 may be shaped as truncated pyramids, the sides 24-7 and 22-8 of the teeth 24-1 and 22-1 may engage with one another to produce an axial force.
- the engagement member 22 may be drawn toward engagement member 24 in an axial direction.
- Figure 7 it may be seen how the teeth 22-1 and 24-1 interact with one another when the generator 12 applies a torque load to the engine 14.
- Figure 7 shows a direction of rotation arrow 62 portraying a counterclockwise rotation of the generator 12 and the engine 14.
- Left-hand sides 22-7 of each of the teeth 22-1 may engage with and produce circumferential force on right-hand sides 24-8 of the teeth 24-1.
- the teeth 22-1 and 24-1 may engage with one another to produce an axial force.
- the engagement member 22 may be drawn toward engagement member 24 in an axial direction.
- the inventive engagement members 22 and 24 may provide effective torque transmission under many different operating conditions.
- the generator 12 may be employed as a starter motor.
- the generator 12 may drive the engine 14, i.e., the engagement member 22 may drive the engagement member 24.
- the engine 14 may produce torque load on the generator 12 and the engagement member 24 may drive the engagement member 22.
- the engagement member 22 may again drive the engagement member 24.
- each of the teeth 22-1 and 24-1 may be angularly displaced relative to the recesses 22-2 and 24-2.
- Each of the recesses 22-2 and 24-2 may have a circumferential width greater than that of each of the teeth 22-1 and 24-1. In the case of the exemplary embodiment described herein, each of the recesses 22-2 and 24-2 may be twice as wide as the respective teeth 24-1 and 22-1.
- the distal width of the recesses 22-2 and 24-2 need only be greater than the distal width of the teeth 22-1 and 24-1 in order to allow for operations of the disengagement assembly 10.
- the distal ends 22-6 and 24-6 of the recesses 22-2 and 24-2 may be wider than the distal ends 22-4 and 24-4 of the teeth 22-1 and 24-1.
- the teeth 22-1 and 24-1 may require only a few degrees of angular displacement relative to one another before the teeth 22-1 and 24-1 may freely move axially relative to one another.
- the disconnect assembly 11 may also include a locking mechanism 42 for locking inner ball screw 16 in place after inner ball screw 16 has moved laterally/axially away from the engine 14 to disengage generator 12 from the engine 14 or its gearbox 13.
- lock mechanism 42 As seen in Figure. 1 , one example of lock mechanism 42 is shown whereby the lock may be a simple key or pin 42-1 whose bottom is urged up momentarily by a slanted back shoulder 16-4 at a proximal end of inner ball screw 16, and then falls back down once slanted back tooth 16-4 passes key 42-1, thereby ensuring that inner ball screw 16 is held in place by lock 42 (i.e. cannot reverse direction) until key 42-1 is re-set.
- the re-setting of lock 42 may be performed manually by an operator which may be achieved manually on the ground by releasing lock 42 such as by causing key 42-1 to be lifted. This may allow springs 43 to push inner ball screw 16 back to its normal position engaged to the engine.
- inner ball screw 16 automatically may revert to its engagement position by rotating through ball track 30 in a reverse direction and sliding axially.
- the generator 12 may be then re-engaged to the gear box 13 or the engine 14 for future normal operation.
- disconnect mechanism 11 may be outside of a housing 12-1 of generator 12 and may have its own housing (not shown), it is also contemplated by the present invention that in certain embodiments disengagement/disconnect assembly 11 may also be subsumed within and utilize housing 12-1 of generator 12.
- FIG. 9 is a flow chart, it may be seen that the present invention also envisions a method 900 of driving a rotating machine such as a variable frequency generator with an engine and disengaging the generator in the event of a malfunction of the generator.
- engagement members may be interlockingly engaged (e.g., the engagement members 22 and 24 may be engaged with interlocking of the teeth 22-1 and 24-1 into the recesses 22-2 and 24-2).
- torque may be applied to the engagement members to produce an axial force (i.e., angled sides 22-7, 22-8, 24-7 and 24-8 may produce axial force upon application of torque on the engagement members 22 and 24).
- a malfunction of the generator may be detected.
- an axial withdrawal mechanism may be activated (a pilot may activate a solenoid 40 to apply a brake 38 and produce axial motion of the engagement member 22 through operation of a ballscrew assembly).
- angular and axial displacement between the engagement members may provide for disengagement of the engine from the generator (e.g., the inner ball screw 16 may produce axial force on the engagement member 22 sufficient to overcome the axial force produced by the angled sides of the teeth 22-1 and 24-1)
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- Engineering & Computer Science (AREA)
- General Engineering & Computer Science (AREA)
- Mechanical Engineering (AREA)
- Connection Of Motors, Electrical Generators, Mechanical Devices, And The Like (AREA)
Abstract
A disengagement/disconnect assembly (11) for disengaging a generator (10) from a gear box (13) may include an inner ball screw (16) having an angled threading on an outer surface thereof and surrounding and operatively engaged to a rotating generator drive shaft (18) to cause rotation of the inner ball screw. The inner ball screw may be attached to an engagement member (22) having undercut and interlockable teeth (22-1) engaged to corresponding teeth (24-1) of an engagement member (24) of the gear box. An outer ball screw (26) may surround and normally rotate with the inner ball screw. A helical ball track (30) may be formed between the inner and outer ball screws. A brake (38) may be provided for slowing or stopping rotation of the outer ball screw so that the inner ball screw rotates relative to the outer ball screw along the ball track and slides axially away from the gear box thereby disengaging the generator from the gear box drive shaft.
Description
- The present invention generally relates to apparatus and methods for disengaging generators and other rotating machines from a prime mover and, more particularly, to apparatus and methods of disengaging an aircraft generator from an engine or gear box to prevent damage to the engine or gear box.
- In the aerospace industry, aircraft receive electric power from generators. The generators may be coupled to the main engine or to auxiliary power units through a gear box. Known designs of generators have a generator drive shaft that includes some kind of shear section that is based on safe operational capability of the gearbox. In the event that the generator malfunctions, this shear section operates and protects the gear box from continuing to rotate under an unacceptable load from a malfunctioning generator that may have stopped rotating. For constant speed generators, the design of the shear section is not difficult - it is easy to design a shear section to meet one speed. However, with the evolution of variable frequency generators (VFG), where failure can occur over a range of speeds, it is rather difficult to design a shear section that can protect the gear box regardless of the multiple possible speeds of the generator.
- It is therefore useful that some other means should be incorporated into the design of the generator that would help protect the gear box. If, for example, there is a minor fault with the generator and it is not producing any power but rather is rotating like a load on the gear box, it is desirable that the generator be de-coupled from the gear box.
- It is also useful that such a protection means should not interfere with proper engagement of the generator with the gearbox irrespective of whether a generator shaft is producing load on the gearbox or alternatively when the gearbox may be producing mechanical load on the generator shaft.
- As can be seen, there is a need to disengage the generator from the gear box as needed when the generator malfunctions. Furthermore, there is a need to have such a disengaging mechanism that is re-settable by the operator or maintenance personnel of the aircraft when the problem with the generator is fixed or addressed. It is also required that the disconnect mechanism not disengage unnecessarily and not inadvertently engage when disconnected.
- In one aspect of the present invention a dis-engageable generator drive system comprises a first engagement member coupled to a generator, and a second engagement member coupled to an engine. The engagement members have a plurality of circumferentially disposed teeth. The teeth have a distal circumferential width at their distal ends and a proximal circumferential width at their proximal ends wherein the distal circumferential width is greater than the proximal circumferential width.
- In a further aspect of the invention a disengagement assembly for disengaging a generator from an engine comprises an axially displaceable engagement member. The engagement member has a plurality of circumferentially disposed teeth. The teeth have a distal circumferential width at their distal ends and proximal circumferential width at their proximal ends wherein the distal circumferential width is greater than the proximal circumferential width.
- In another aspect of the invention a method of driving a generator with an engine comprises the steps of Interlockingly engaging the engine with an inner ball screw having an angled threading on an outer surface thereof, engaging the inner ball screw with an outer ball screw that rotates with the inner ball screw, including an angled ball track between the inner ball screw and the outer ball screw on which a ball bearing travels, and actuating a brake to slow or stop rotation of the outer ball screw so that the inner ball screw rotates relative to the outer ball screw along the ball track and slides axially away from the engine thereby disengaging the generator from the engine..
- These and other features, aspects and advantages of the present invention will become better understood with reference to the following drawings, descriptions and claims.
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Figure 1 is a sectional view of a drive system wherein a generator is in its normal state engaged with an engine in accordance with the invention; -
Figure 2 is a sectional view of the disengagement assembly ofFigure 1 wherein the generator is disengaged from the engine in accordance with the invention; -
Figure 3 is a perspective view of a generator-side engagement member in accordance with the invention; -
Figure 4 is a perspective view of an engine-side engagement member in accordance with the invention; -
Figure 5 is a graphical representation of teeth and recesses of the engagement members ofFigures 3 and 4 in accordance with the invention; -
Figure 6 is a graphical representation of teeth and recesses of the engagement members ofFigures 3 and 4 in accordance with the invention; -
Figure 7 is another graphical representation of teeth and recesses of the engagement members ofFigures 3 and 4 in accordance with the invention; -
Figure 8 is a graphical representation of teeth and recesses of the engagement members ofFigures 3 and 4 in a disengaged state in accordance with the invention; and -
Figure 9 is a flow chart showing a method in accordance with the present invention. - The following detailed description is of the best currently contemplated modes of carrying out the invention. The description is not to be taken in a limiting sense, but is made merely for the purpose of illustrating the general principles of the invention, since the scope of the invention is best defined by the appended claims.
- The present invention generally provides a disengagement assembly for a rotating machine, such as an aircraft generator, for disengaging the generator from an engine or gear box. Typically, the drive shaft of the generator may be rotating and operatively engaged to the drive shaft of the gear box. When the generator is not working properly, for example in an aircraft, the disengagement assembly may allow a pilot to disengage the generator from the gear box. The disengagement assembly may be a modular or standalone assembly having its own housing separate from the housing of the generator, or alternatively the disengagement assembly may be subsumed within the housing of the generator. The disengagement assembly may be used in aircraft and may be re-settable manually on the ground after repair of the generator.
- In contrast to the prior art, which does not use interlocking engagement teeth, the disengagement assembly of the present invention may utilize a ball screw mechanism to provide a desired axial positioning of novel engagement teeth which maintain an interlocking relationship with one another irrespective of direction of torque application during proper operation of the generator. The interlocking teeth may disengage from one another in the event of a malfunction of the generator. In further contrast to the prior art, in which the disconnect mechanism has to self-destruct in order to function; the disengagement assembly of the present invention may be resettable and reusable.
- As seen from
Figures 1 and2 , agenerator drive system 10 may be provided with adisengagement assembly 11 for disengaging avariable frequency generator 12 from agear box 13 of a prime mover orengine 14. Thedisengagement assembly 11 may comprise a rotatableinner ball screw 16 that has angled threading 16-1 on an outer surface 16-2 ofinner ball screw 16. - Since
inner ball screw 16 may be hollow,inner ball screw 16 may surround and may be operatively engaged to agenerator drive shaft 18 so that the rotation ofgenerator drive shaft 18 on anaxis 19 may cause rotation ofinner ball screw 16. In this regard, there may be radially protrudingsplines 20 between the surface ofgenerator drive shaft 18 and an inner surface 16-3 ofinner ball screw 16. Thesplines 20 or another suitable structure may serve to transfer rotational force of thegenerator drive shaft 18 toinner ball screw 16. -
Inner ball screw 16 may have anengagement member 22, at an end distal to thegenerator 12. Thisengagement member 22 may be normally engaged to acorresponding engagement member 24 which may be connected to thegearbox 13 or optionally to theengine 14 if a gearbox is not utilized. -
Disengagement assembly 11 may also include anouter ball screw 26 which may surround and may normally rotate withinner ball screw 16. As seen inFigure 2 ,outer ball screw 26 may have associated with it one ormore balls 28, called ball bearings, that travel on an angled ball track 30 that exists between theinner ball screw 16 andouter ball screw 26. In one exemplary embodiment, there may be between approximately five and seven such balls depending upon the design requirement. The angled ball track 30 may be formed from threading 16-1 on theinner ball screw 16 and outer threading 26-1 formed on theouter ball screw 26. The fact that the ball track 30 is angled means that ball track 30 has some axial component rather than simply being a series of revolutions aroundinner ball screw 16. -
Disengagement assembly 11 may also include abrake 38 that may be capable of slowing or stopping rotation ofouter ball screw 26. When thebrake 38 slows or stops rotation ofouter ball screw 26, since normallyinner ball screw 16 rotates together withouter ball screw 26, this slowing or stopping of the rotation ofouter ball screw 26 may causeinner ball screw 16 to rotate relative toouter ball screw 26 along ball track 30 and simultaneously slide axially away from theengine 14 thereby disengaging thegenerator 12 from theengine 14. Wheninner ball screw 16 slides axially away fromengine 14,inner ball screw 16 may be sliding ongenerator drive shaft 18, and more precisely onsplines 20 between the surface ofgenerator drive shaft 18 and inner surface 16-3 ofinner ball screw 16. - Accordingly,
outer ball screw 26 may be capable of rotation andinner ball screw 16 may be capable of both rotation and axial movement. Thebrake 38 may be connected to asolenoid 40 that may be remotely actuatable by an aircraft pilot whengenerator 12 malfunctions. Other arrangements may easily be imagined wherebybrake 38 may be controlled directly or indirectly with other mechanisms. - Referring now to
Figures 3 and 4 it may be seen that theengagement member 22 may include interlockable teeth 22-1 and thecorresponding engagement member 24 of the gear boxdrive shaft adaptor 14 may also include interlockable teeth 24-1 that mate with the teeth 22-1. In an exemplary embodiment shown inFigure 3 the teeth 22-1 may be positioned circumferentially around theengagement member 22. It may also be noted that while an exemplary number of eight of the teeth 22-1 are shown inFigure 3 , each of the teeth 22-1 covers only about 15 degrees of angular displacement around the circumference of theengagement member 16. Recesses 22-2 between the teeth 22-1 cover a larger portion of the circumference than the teeth 22-1. Each of the recesses 22-2 may cover about thirty degrees of angular displacement of the circumference. In this regard it may be seen that recesses 22-2 may be about twice as wide as their respective adjacent teeth 22-1. Theengagement member 24 shown inFigure 4 may also be provided with similar teeth 24-1 and recesses 24-2 which may interconnect and interlock with the teeth 22-1 and recesses 22-2 of theengagement member 22. - Referring now to
Figures 5 ,6 and7 , a novel relationship of the teeth 22-1 and 24-1 and the recesses 22-1 and 24-2 may be appreciated. Referring particularly toFigure 5 , consider first a configuration ofengagement member 22. Each of the teeth 22-1 may be formed with a proximal end 22-3 smaller than a distal end 22-4. In other words, each of the teeth 22-1 may be formed with a profile that resembles a truncated pyramid. Each of the recesses 22-2 may be formed with a proximal end 22-5 larger than a distal end 22-6. Tooth sides 22-7 may be formed at an angle A relative to anaxis 19 of thegenerator 12 ofFigure 1 . Tooth sides 22-8 may be formed at the angle B relative to theaxis 19. - The
engagement member 24 may have its teeth 24-1 and its recesses 24-2 formed in the same manner as the teeth 22-1 and the recesses 22-2 of theengagement member 22. -
Figures 5 ,6 and7 are intended to provide a readily understandable graphical representation of the interlocking nature of the teeth 22-1 and 24-1 and the recesses 22-2 and 24-2. As suchFigures 5 ,6 and7 may not show their respective objects in scale. In an actual exemplary embodiment of the invention, the angles A and B may be equal in magnitude and opposite in direction relative to theaxis 19. The angles A and B may be between about three degrees and about one degree. Each of the teeth 22-1 and 24-1 may have a height H of about 0.050 inch to about 0.150 inch. In a typical exemplary embodiment theengagement member 22 may have a diameter of between about 2 inches to about 3 inches. In this context each of the recesses 22-2 and 24-2 may have a distal width of between about 0.50 inch and 0.80 inch. Each of the teeth 22-1 and 24-1 may have a distal width of about 0.25 inch to about 0.40 inch. - Referring now particularly to
Figure 6 , it may be seen how the teeth 22-1 and 24-1 interact with one another when theengine 14 or itsgearbox 13 may apply a torque load to thegenerator 12, i.e. whenengagement member 24 drivesengagement member 22.Figure 6 shows a direction ofrotation arrow 62 portraying a counterclockwise rotation of thegenerator 12 and theengine 14. Left-hand sides 24-7 of each of the teeth 24-1 may engage with and produce circumferential force on right-hand sides 22-8 of the teeth 22-1. Because each of the teeth 22-1 and 24-1 may be shaped as truncated pyramids, the sides 24-7 and 22-8 of the teeth 24-1 and 22-1 may engage with one another to produce an axial force. In other words, theengagement member 22 may be drawn towardengagement member 24 in an axial direction. - As torque load increases, the axial force increases correspondingly. In a typical aircraft generating system rotational speeds of 24,000 revolutions per minute (rpm) may develop. Torque loads of 300 foot-pounds may also be encountered, increasing torque and speed often results in increased vibration. Increased vibration may increase a risk that the
engagement members - Referring now particularly to
Figure 7 , it may be seen how the teeth 22-1 and 24-1 interact with one another when thegenerator 12 applies a torque load to theengine 14.Figure 7 shows a direction ofrotation arrow 62 portraying a counterclockwise rotation of thegenerator 12 and theengine 14. Left-hand sides 22-7 of each of the teeth 22-1 may engage with and produce circumferential force on right-hand sides 24-8 of the teeth 24-1. As described with respect toFigure 6 , the teeth 22-1 and 24-1 may engage with one another to produce an axial force. In other words, theengagement member 22 may be drawn towardengagement member 24 in an axial direction. - Considering both
Figures 6 and7 it may be seen that irrespective of whether thegenerator 12 is being driven by torque from theengine 14 or is producing torque force on theengine 14, the teeth 22-1 and 24-1 may remain engaged. Additionally, it may be seen that the teeth 22-1 and 24-1 may produce axial force in the presence of torque provided by either thegenerator 12 or theengine 14. Thus, theinventive engagement members generator 12 may be employed as a starter motor. In that case, thegenerator 12 may drive theengine 14, i.e., theengagement member 22 may drive theengagement member 24. Conversely, during steady-state operation of theengine 14, theengine 14 may produce torque load on thegenerator 12 and theengagement member 24 may drive theengagement member 22. In the event of engine deceleration, theengagement member 22 may again drive theengagement member 24. - Referring now to
Figure 8 and back toFigure 2 , it may be seen that upon application of thebrake 38, theengagement members engagement members figure 8 . Each of the teeth 22-1 and 24-1 may be angularly displaced relative to the recesses 22-2 and 24-2. Each of the recesses 22-2 and 24-2 may have a circumferential width greater than that of each of the teeth 22-1 and 24-1. In the case of the exemplary embodiment described herein, each of the recesses 22-2 and 24-2 may be twice as wide as the respective teeth 24-1 and 22-1. However, it should noted that the distal width of the recesses 22-2 and 24-2 need only be greater than the distal width of the teeth 22-1 and 24-1 in order to allow for operations of thedisengagement assembly 10. In other words, the distal ends 22-6 and 24-6 of the recesses 22-2 and 24-2 may be wider than the distal ends 22-4 and 24-4 of the teeth 22-1 and 24-1. The teeth 22-1 and 24-1 may require only a few degrees of angular displacement relative to one another before the teeth 22-1 and 24-1 may freely move axially relative to one another. - The
disconnect assembly 11 may also include alocking mechanism 42 for locking inner ball screw 16 in place afterinner ball screw 16 has moved laterally/axially away from theengine 14 to disengagegenerator 12 from theengine 14 or itsgearbox 13. - As seen in
Figure. 1 , one example oflock mechanism 42 is shown whereby the lock may be a simple key or pin 42-1 whose bottom is urged up momentarily by a slanted back shoulder 16-4 at a proximal end ofinner ball screw 16, and then falls back down once slanted back tooth 16-4 passes key 42-1, thereby ensuring thatinner ball screw 16 is held in place by lock 42 (i.e. cannot reverse direction) until key 42-1 is re-set. The re-setting oflock 42 may be performed manually by an operator which may be achieved manually on the ground by releasinglock 42 such as by causing key 42-1 to be lifted. This may allowsprings 43 to push inner ball screw 16 back to its normal position engaged to the engine. Accordingly, when the lock 36 is later manually released, inner ball screw 16 automatically may revert to its engagement position by rotating through ball track 30 in a reverse direction and sliding axially. Thegenerator 12 may be then re-engaged to thegear box 13 or theengine 14 for future normal operation. - Although as seen from
Figures 1-2 , theentire disconnect mechanism 11 may be outside of a housing 12-1 ofgenerator 12 and may have its own housing (not shown), it is also contemplated by the present invention that in certain embodiments disengagement/disconnect assembly 11 may also be subsumed within and utilize housing 12-1 ofgenerator 12. - Referring now to
Figure 9 , which is a flow chart, it may be seen that the present invention also envisions amethod 900 of driving a rotating machine such as a variable frequency generator with an engine and disengaging the generator in the event of a malfunction of the generator. In astep 902, engagement members may be interlockingly engaged (e.g., theengagement members step 904, torque may be applied to the engagement members to produce an axial force (i.e., angled sides 22-7, 22-8, 24-7 and 24-8 may produce axial force upon application of torque on theengagement members 22 and 24). In astep 906, a malfunction of the generator may be detected. In astep 908 an axial withdrawal mechanism may be activated ( a pilot may activate asolenoid 40 to apply abrake 38 and produce axial motion of theengagement member 22 through operation of a ballscrew assembly). In astep 910, angular and axial displacement between the engagement members may provide for disengagement of the engine from the generator (e.g., theinner ball screw 16 may produce axial force on theengagement member 22 sufficient to overcome the axial force produced by the angled sides of the teeth 22-1 and 24-1) - It should be understood, of course, that the foregoing relates to exemplary embodiments of the invention and that modifications may be made without departing from the spirit and scope of the invention as set forth in the following claims.
Claims (5)
- A disengageable generator drive system (10) comprising:a first engagement member (22) coupled to a generator (12);a second engagement member (24) coupled to a prime mover (14);the engagement members (22 and 24) having a plurality of circumferentially disposed teeth (22-1 and 24-1);the teeth (22-1 and 24-1) having a distal circumferential width at their distal ends (22-4 and 24-4) and a proximal circumferential width at their proximal ends (22-3 and 24-3); andwherein the distal circumferential width is greater than the proximal circumferential width.
- The drive system (10) of claim 1;
wherein the teeth (221- and 24-1) are equally sized and equally distributed circumferentially of their respective engagement members (22 and 24);
wherein the engagement members (22 and 24) are provided with circumferentially disposed recesses (22-2 and 24-2) between the teeth (22-1 and 22-4);
wherein the recesses (22-2 and 24-2) have sides (22-7 and 22-8; 24-7 and 24-8) that are comprised of sides (22-7 and 22-8; 24-7 and 24-8) of the teeth (22-1 and 24-1); and
wherein the recesses (22-2 and 24-2) have a circumferential width greater than the distal circumferential width of the teeth (22-1 and 24-1). - The drive system (10) of any one or more of claims 1-2 wherein the teeth (22-1 and 24-1) have at least one of their sides oriented at an angle of about one degree to about three degrees relative to an axis (19) of the generator (12).
- The drive system (10) of any one or more of claims 1-3:
wherein the teeth (22-1 and 24-1) have two of their circumferentially opposing sides (22-7 and 22-8; 24-7 and 24-8) oriented at an angle relative to an axis (19) of the generator (12); and
wherein the two sides are oriented at angles that are equal in magnitude and opposite in direction. - The drive system (10) of any one or more of claims 1-4 wherein the engagement members (22 and 24) exert axial force on one another in a presence of a torque load on either of the engagement members (22 and 24).
Applications Claiming Priority (1)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
US12/042,137 US7946403B2 (en) | 2008-03-04 | 2008-03-04 | Mechanical disconnect dual-sided interlocking teeth |
Publications (1)
Publication Number | Publication Date |
---|---|
EP2098741A2 true EP2098741A2 (en) | 2009-09-09 |
Family
ID=40716598
Family Applications (1)
Application Number | Title | Priority Date | Filing Date |
---|---|---|---|
EP09153008A Withdrawn EP2098741A2 (en) | 2008-03-04 | 2009-02-17 | Mechanical disconnect dual-sided interlocking teeth |
Country Status (2)
Country | Link |
---|---|
US (1) | US7946403B2 (en) |
EP (1) | EP2098741A2 (en) |
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US20090224727A1 (en) | 2009-09-10 |
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